Pre-heat oven to fan assisted 160C / 180C / 350F / gas 4.
Lightly oil a 6 cup silicon muffin tin (including the top).
Whisk the eggs and yogurt together till they are well combined and the mixture is smooth. An electric whisk may be easier for kids to use for this stage.
Add in all the other ingredients and mix well.
Add equal amounts of the frittata mixture to each muffin cup.
Bake in the oven for about 20 mins till golden and cooked through.